export declare function streamFetch(url: string): Promise<Uint8Array<ArrayBuffer> | undefined>;
/**
 * 流式下载文本或Json
 * @param url
 * @returns
 */
export declare function streamFetchText(url: string): Promise<string | undefined>;
/**
 * 获取二进制文件（图片、pdf等）
 * @param url
 * @param mimeType 默认'application/octet-stream'  图片为：'image/jpeg'、'image/png'
 * @returns
 */
export declare function streamFetchBlob(url: string, mimeType?: string): Promise<Blob | undefined>;
/**
 * 大文件上传——数据流分块
 * @param file
 * @param url
 * @param processCallBack
 * @returns
 */
export declare function streamFetchUploadFile(file: File, url?: string, processCallBack?: Function): Promise<any>;
/**
 * 流式加载大图，并渐进式显示图片
 * @param canvas
 * @param url
 * @param chunkSize 分块大小，默认为128K
 * @returns
 */
export declare function streamFetchLoadImage(canvas: HTMLCanvasElement, url: string, chunkSize?: number): Promise<undefined>;